In many telecommunication systems, communications networks are used to exchange messages among several interacting spatially-separated devices. Networks may be classified according to geographic scope, which could be, for example, a metropolitan area, a local area, or a personal area. Such networks would be designated respectively as a wide area network (WAN), metropolitan area network (MAN), local area network (LAN), wireless local area network (WLAN), near area network (NAN) or personal area network (PAN). Networks may also differ according to the switching/routing technique used to interconnect the various network nodes and devices (e.g., circuit switching vs. packet switching), the type of physical media employed for transmission (e.g., wired vs. wireless), and the set of communication protocols used (e.g., Internet protocol suite, SONET (Synchronous Optical Networking), Ethernet, etc.).
Some devices use ANT protocol to communicate over wireless networks. ANT is a wireless sensor network protocol operating in the 2.4 GHz ISM band. ANT's low computational overhead and high efficiency enable ultra-low power and scalable wireless connectivity. ANT is embedded in a wide variety of devices including mobile phones, handheld GPS devices, sensors, medical devices, and fitness equipment for healthcare, fitness, communications, and industrial applications.
In many wireless communication protocols, including ANT, devices use syncwords to synchronize communicating devices. A syncword is a sequence of bits that identifies a device, and is known to both the sending and receiving device. Sending devices include the syncword for the intended recipient in transmitted signals. Intended recipients correlate the signal syncword with their device syncword. When the computed correlation is high (equals or exceeds an acquisition threshold value), the message is assumed to be intended for the device. When the correlation is less than the acquisition threshold value, the device assumes that the message is not intended for it. Due to a variety of communication and device imperfections which can affect a transmitted signal and the processing of the signal at a device receiving the signal, the received signal is not always identified as a match for a syncword even when it is supposed to match (“missed detects”). In other cases, the received signal may be incorrectly identified as a match for the device even when it is not supposed to match (“false alarms”). Accordingly, methods and apparatuses that can improve the accuracy of syncword acquisition are desired.